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INTRODUCTION

Transmission of GI infections can be reduced by attention to good hand hygiene. Hand washing can reduce the incidence of diarrheal disease by approximately 30% in both high- and low-income countries.2 The provision of alcohol-based hand sanitizer and educational materials can reduce GI illnesses in child care centers,3 and a multifactorial intervention including hand sanitizer and surface disinfection similarly reduces illness due to enteric pathogens in elementary school students.4

Rotavirus accounts for a large majority of severe cases and contributes significantly to hospitalizations in developed countries. Two live oral rotavirus vaccines, marketed as RotaTeq® and Rotarix®, are currently licensed for use in the United States and numerous other countries. These vaccines are recommended by the World Health Organization for immunization of children worldwide. They have been introduced into the immunization programs of >50 countries. Routine rotavirus vaccination, which began in the United States in 2006, has resulted in an approximately 80% reduction in rotavirus-related hospitalizations and ED visits for rotavirus among immunized children.5,6 Although a prospective postlicensure study of more than 200,000 doses identified an increase in the rate of intussusception after vaccination (attributable risk ~5.3 per 100,000 infants vaccinated); this increased risk must be weighed against the benefits of preventing rotavirus-associated illness.7

Although the clinical diagnosis of gastroenteritis requires the presence of diarrhea, many infants present with isolated vomiting. This chapter focuses on one of the most frequent and important causes of vomiting and diarrhea in children, gastroenteritis, and will also review other important causes of these symptoms.

VOMITING

Vomiting is the forceful act of expelling gastric contents through the mouth. It is controlled by the vomiting center in the reticular formation of the medulla and the chemoreceptor trigger zone underlying the floor of the fourth ventricle. Trigger areas that excite the CNS vomiting centers are found in the pharynx, cardiac vessels, peritoneum, bile ducts, and stomach. Vomiting results when the stomach relaxes, the gastric pylorus constricts, and the contractions of surrounding muscles cause expulsion of the gastric contents. Acute vomiting is usually caused by a self-limited viral illness. Nonetheless, serious diagnoses that need to be considered include infections, metabolic abnormalities, neurologic processes, acute surgical/GI diseases, or other major organ system dysfunction. The differential diagnosis of vomiting is age specific (Table 128-1). Bilious or bloody vomitus, hematochezia, or significant abdominal pain should trigger concerns of a disease process other than simple viral gastroenteritis or a potential complication of viral gastroenteritis (Tables 128-2 and 128-3).